Auto-detect GSL paths in setup.py to fix compilation failures when CFLAGS/LDFLAGS are unset

[Copilot]

GSL installed in non-standard prefixes (Homebrew on macOS, conda on Windows) causes fatal error: 'gsl/gsl_math.h' file not found when users haven't manually set CFLAGS/LDFLAGS.

setup.py

After the existing gsl-config --version call, invoke gsl-config --cflags and gsl-config --libs and inject discovered paths directly into both C extensions via include_dirs, library_dirs, and runtime_library_dirs (rpath on Unix/macOS; empty on Windows).

Key details:

• All platforms: runs on Unix/macOS/Windows; uses shell=True on Windows for .bat execution
• Deduplication: skips paths already in CFLAGS/LDFLAGS (Unix) or INCLUDE/LIB (Windows)
• Validation: paths are only used if they contain actual GSL files — gsl/gsl_math.h for include dirs, libgsl* or gsl.lib for lib dirs — silently skipping garbage output (e.g. when CONDA_PREFIX is unset on Windows)

CI

build.yml (Linux/macOS):

• Splits macOS GSL+OpenMP install step: software install always runs; env-var export is skipped for all macos-* jobs with test_energy_jacobi_conservation or from_name in TEST_FILES (robust to runner version changes)
• A companion step sets only the libomp paths for those jobs, since OpenMP location isn't auto-detected

build_windows.yml:

• Splits "Set GSL environment variables": a PATH-only step always runs (exposes gsl-config.bat and exports CONDA_PREFIX so the .bat resolves paths correctly); INCLUDE/LIB/LIBPATH is skipped for the test_actionAngle.py Python 3.14 job to exercise auto-detection

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[jobovy]

pre-commit.ci autofix

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.91%. Comparing base (5b3ae02) to head (15ce76f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   99.91%   99.91%           
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  Files         215      215           
  Lines       30920    30920           
  Branches      613      613           
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  Hits        30893    30893           
  Misses         27       27           

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[jobovy]

@copilot Actually, the gsl-config.bat file seems to allow gsl-config to be run with the --cflags and --libs arguments, so we can probably run it on Windows as well. Test it in the build_windows.yml workflow in a similar way as for macs.

[Copilot]

@copilot Actually, the gsl-config.bat file seems to allow gsl-config to be run with the --cflags and --libs arguments, so we can probably run it on Windows as well. Test it in the ``build_windows.yml`...

Done in 4d87e23. The not WIN32 guard is removed so gsl-config --cflags/--libs is now called on Windows too (with shell=True for .bat execution). Windows-specific details: deduplication checks INCLUDE/LIB env vars instead of CFLAGS/LDFLAGS, and quoted paths from gsl-config.bat output are stripped. runtime_library_dirs is left empty on Windows (no rpath concept).

In build_windows.yml, the "Set GSL environment variables" step is split: a PATH-only step (always runs, making gsl-config.bat accessible) and the INCLUDE/LIB/LIBPATH step (skipped for the test_actionAngle.py Python 3.14 job to test auto-detection).

[jobovy]

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